Friction is a force that resists relative motion between solids or fluids.

“Air Friction” is more correctly known as “Drag” which comes in three forms: Parasitic, Lift-induced and Wave drag.

And wave drag is the result of, you guessed it, compression shock

So IT IS friction… unless you are in this case referring to a specific form of friction that I am unfamiliar with

]]>By: Levi in NYhttp://blogs.discovermagazine.com/badastronomy/2011/10/25/final-rosat-came-down-in-the-bay-of-bengal/#comment-312626
Thu, 27 Oct 2011 02:54:27 +0000http://blogs.discovermagazine.com/badastronomy/?p=39838#comment-312626How amazingly ironic would it be if it had crashed on North Sentinel Island? Looks like it was really close.

As for spy satellites tracking ROSAT’s descent, I’d expect most of them would be focused on other things and that wouldn’t exactly be top priority for them as they’d be looking elsewhere?

]]>By: Messier Tidy Upperhttp://blogs.discovermagazine.com/badastronomy/2011/10/25/final-rosat-came-down-in-the-bay-of-bengal/#comment-312624
Wed, 26 Oct 2011 14:55:33 +0000http://blogs.discovermagazine.com/badastronomy/?p=39838#comment-312624@11. George : Okay, that interpretation of what Tara Li was saying does make sense I guess when you put it like that – although I was kinda hoping (& still am) to hear from her directly on that. Thanks.

PS. Yeah, I always have been a lousy typer. Mea culpa. What’s “center” in deutsch anyhow?

I am not a native English speaker but I can very easily understand what Tara Li said. I’ll ty to re-phrase it for you, as you got her statemets completely wrong:

TL: “There’s enough of the bloody spy sats, …”

= “There are plenty of US owned military reconnaissance / early warning satellites in orbit that were able to trace the heat signature of the re-entering ROSAT…”

TL: “…and the signature of a significant re-entry is going to be so different from a missile launch, they could post when & where with no real impact on security.”

= “…so the USG knew withing almost real-time when and where ROSAT re-entered but refuses to let the rest of the world know as they are paranoid about disclosing their capabilities – which everybody already knows they have”

By the way, it’s officially the “German Aerospace Center”, not “Centre” I worked there for 10 years.

@4. Chris : “But were any fish hit? No one ever cares about the fish.”

Unlikely any fish were hit unless they were especially unlucky flying fish!

Once ROSAT hit the ocean it’s momentum would, I’d expect, have been much slower and gentler as it sank and the fish would probably have been easily able to move out the way.

Jellyfish aside.

@7. Tara Li :

There’s enough of the bloody spy sats, …

For Your Information, ROSAT (short name for ROentgen SATellite) was an astronomical scientific research satellite not a spy satellite. It was a mission designed and run by the German Aerospace Centre to study the sky in X-rays, a space telescope. Click on my name for a link to their website.

…and the signature of a significant re-entry is going to be so different from a missile launch, they could post when & where with no real impact on security.

Please can you rephrase, expand upon or otherwise clarify that last part of your sentence there because I honestly can’t understand what you are trying to say or what point you are presumably trying to make. You are not making sense there – to me at least – at all.